Functional Equivalency Trajectories of the Restored Gog‐Le‐Hi‐Te Estuarine Wetland

Abstract

Assessing performance of restored and created wetlands for compensatory mitigation and restoration poses a mismatch between long‐term processes and the short‐term expediency of management decisions. If they were predictable, patterns in the temporal development of important wetland processes could reduce long‐term uncertainty of the outcome of restoration projects. To test our ability to predict long‐term trends and patterns in the development of a restored wetland based on the first 7 yr of its development, we analyzed 16 ecosystem functional attributes of the Gog‐Le‐Hi‐Te Wetland, in the Puyallup River estuary, Puget Sound, Washington, USA. This estuarine wetland system was restored to tidal inundation in 1986. Only a few of the 16 ecosystem attributes analyzed showed functional trajectories toward equivalency with natural wetlands, and many were inconclusive or suggested disfunction relative to reference wetlands. Natural variability among reference sites also inhibited our ability to interpret an expected asymptote in developmental trajectories. The ability of wetland managers to assess compensatory‐mitigation success over short‐term (e.g., regulatory) timeframes depends upon the selection of wetland attributes that can predict long‐term trends in the development of the restored/created system. However, we are hampered by a basic lack of long‐term data sets describing the patterns, trends, and variability in natural wetland responses to disturbance, as well as natural variability in wetland attributes in presumably mature wetland communities. Ultimately, it may be necessary to supplant our descriptive means of assessing functional equivalency with simple, controlled manipulative experiments or assays, standardized across restoration/mitigation and reference sites.